diff --git a/libavcodec/j2kdec.c b/libavcodec/j2kdec.c
index 22bbb2effd..a02b84b820 100644
--- a/libavcodec/j2kdec.c
+++ b/libavcodec/j2kdec.c
@@ -957,6 +957,8 @@ static int decode_codestream(Jpeg2000DecoderContext *s)
         switch (marker){
         case JPEG2000_SIZ:
             ret = get_siz(s);
+            if (!s->tile)
+                s->numXtiles = s->numYtiles = 0;
             break;
         case JPEG2000_COC:
             ret = get_coc(s, codsty, properties);
diff --git a/libavcodec/jpeg2000dec.c b/libavcodec/jpeg2000dec.c
index a43cc7e7c6..0735da12f0 100644
--- a/libavcodec/jpeg2000dec.c
+++ b/libavcodec/jpeg2000dec.c
@@ -1181,6 +1181,8 @@ static int jpeg2000_read_main_headers(Jpeg2000DecoderContext *s)
         switch (marker) {
         case JPEG2000_SIZ:
             ret = get_siz(s);
+            if (!s->tile)
+                s->numXtiles = s->numYtiles = 0;
             break;
         case JPEG2000_COC:
             ret = get_coc(s, codsty, properties);